add_force

This keyword is used to add force on atoms in a selected group at each step during a run.

Syntax

This keyword is used in one of the following two ways:

add_force <group_method> <group_id> <Fx> <Fy> <Fz> # usage 1
add_force <group_method> <group_id> <add_force_file> # usage 2

• Force is added to atoms in group group_id of group method group_method.

• In the first usage, the constant force with components Fx, Fy, and Fz is added on each selected atom.

• In the second usage, a series of forces specified in the file add_force_file will be periodically added on each selected atom.

• Force is in units of eV/Å.

Example 1

Add a constant force of 0.1 eV/Å in the x direction on atoms in group 1 of group method 2:

add_force 2 1 0.1 0 0

Example 2

Add force on atoms in group 2 of group method 0, where the file add_force.txt contains a number of rows of 3 values specifying a sequence of force vectors to be periodically applied during the run:

add_force 0 2 add_force.txt

Note

This keyword can be used multiple times during a run.